Liquid-crystalline polyester which is excellent in dielectric property at high-frequency and low water absorption, has received much attention as a material used for electronics substrate. In a film produced by extruding liquid-crystalline polyester, molecular chain of the polyester is significantly oriented along the extruding direction. Due to the orientation, the mechanical strength of the film is anisotropic in the lateral direction (orthogonal to the extruding direction) comparing with the longitudinal direction (extruding direction).
A liquid-crystalline polyester film with small anisotropy can be produced by applying a solution composition containing liquid-crystalline polyester and trifluoroacetic acid over a support and remove the solvent from the spread JP 62-64832 A the solvents used in JP 62-64832 A may be highly corrosive and difficult in handling.
JP 2002-114894 A discloses compositions of liquid-crystalline polyester solution containing solvents such as p-chlorophenol as a low corrosive solvent. It is still desired to develop a solution composition that contains a further low corrosive solvent and easy in handling, and provide a liquid-crystalline polyester film with small anisotropic mechanical strength.